1. Technical Field
The present invention relates generally to concrete structures and related construction methods, and more particularly, to surface drainage systems.
2. Background
Drainage systems are typically incorporated into paved streets, parking lots, airport runways, taxiways and ramps, driveways, and other like surfaces where surface water presents a substantial hazard. Such systems are configured to channel excess rain and ground water from the surface, and are typically comprised of conduits embedded beneath the surface to be drained. The conduit may form a part of a larger network of storm drains, which may transport water to a processing plant prior to discharge, directly discharge into a canal, river, lake, or the ocean, or discharge into small and localized dry wells.
Typically, conduits utilized in conventional surface drainage systems are elongate troughs with U-shaped or V-shaped cross sections. The conduits are disposed within the pavement in a manner that the open top is contiguous with the pavement surface. In order to facilitate gravitational flow, the pavement surface may be slightly sloped. It is understood that the conduits may be defined by the pavement material itself, such as where the pavement material is poured around a form that is later removed. The conduit thus corresponds to the shape of the form. Production of these types of conduits is expensive and time-consuming because of the need to install and remove the forms over extended periods of time. Alternatively, conduits may be stand-alone components constructed of metal, plastic, or other resilient material that are installed into the pavement. These open top conduits are difficult to install because they must be supported in a desired position while the pavement material is poured, particularly in such a position that the open top is flush with the pavement surface. To the extent that support members are utilized to maintain the desired position of the conduit, such components become permanently embedded within the pavement, thereby increasing costs.
Due to the wide open top of conventional drain conduits, grates are fitted thereon to prevent large debris from entering the conduit, to prevent injuries to pedestrians, and to prevent damage to vehicular traffic traveling over the conduit, while still allowing the excess surface water to pass. The grates are generally large and heavy because of the need to support the high load imposed by the traffic. As such, the grates tend to be unsightly and difficult to remove when the inside of the conduit needs to be cleaned. Along these lines, the grates often clog with debris that is likewise difficult to remove. Regardless of being able to support the load of vehicular traffic, the grates are hazardous to pedestrians, particularly to those wearing pointed-heel shoes or open-toe shoes. The heels may become wedged between the grates and cause the person to trip and fall. Or, a person's toes may also become trapped and likewise result in a fall, or worse, toe breakage.
As an alternative to using grates to cover the wide open tops of conventional drain conduits, slotted drains have been contemplated. Slotted drains generally consist of cylindrical pipes embedded beneath the surface, with relatively narrow slots or throats extending upwardly from the pipe to the surface. Thus, it is unnecessary to install a grate over the slots. Despite the small width of the slots, the conduit along which the water is carried to the outlet is large, so large volumes of water can be channeled away from the surface. Because of the specialized construction, slotted drains tend to be expensive. Due to the differences in the coefficient of thermal expansion between the slotted drains and the surrounding concrete, cracking of the concrete is a common problem. Especially problematic are parts of the paving that must conform to the diminutive subparts of the slotted drain, such as the throat and the lip of the opening. In environments where frequent freezing and thawing occur, this problem is further compounded. Furthermore, the above-described problems related to installation and particularly the problems of keeping the openings of the conduit flush with the pavement surface still remain. Support mechanisms added to alleviate the aforementioned problems further add to the cost of the slotted drains. In addition to the need for the surfaces surrounding the conduit openings/slots to be slanted, the conduit itself must be slanted to facilitate the flow of water. Accordingly, the difficulty associated with properly aligning the opening of the slotted drain with the pavement surface is multiplied.
Therefore, there is a need in the art for a surface drainage system that has minimal peripheral components such as throats, supports, and the like. There is also a need in the art for surface drainage systems that reduce dangers to pedestrians, and are visually attractive. There is also a need in the art for a method of constructing a surface drainage system that minimizes repeated alignment corrections, and generally simplifies the procedure.